http://www.smithsonianmag.com/science-nature/forests-around-...
"Birds around Chernobyl have significantly smaller brains that those living in non-radiation poisoned areas; trees there grow slower; and fewer spiders and insects—including bees, butterflies and grasshoppers—live there. Additionally, game animals such as wild boar caught outside of the exclusion zone—including some bagged as far away as Germany—continue to show abnormal and dangerous levels of radiation."
And there are likely plenty more terrible results we don't yet know about.
I didn't say it's all roses, but the wildlife there is thriving because of severe lack of humans. Sure those near the sarcophagus are dangerously mutated, but the scientist in me wonders how the animals will adapt to heightened radiation.
As for fires, there is that, but then again the exclusion zone will spread and there will be more free space for wildlife. People will have to reallocate but on the plus side, more refuge for animals.
The ambient levels of radioactivity are very "livable" in the surroundings of Chernobyl nowadays, plus you have to consider that it's not because radioactivity is detrimental that it prevents animals from breeding and surviving. Only very high levels of radioactivity are known to be fast killers, moderate levels will likely cause more cancers, and low levels are heavily debated (some people saying it causes harm, some others saying it has protective effects on the body as it kills a number of microorganisms).